Effect of TNF-alpha on SMIT mRNA levels and myo-inositol accumulation in cultured endothelial cells.
Previously we have shown that hyperosmolarity increases Na(+)-myo-inositol cotransporter (SMIT) activity and mRNA levels in cultured endothelial cells. Because hyperosmolarity and cytokines, such as tumor necrosis factor-alpha (TNF-alpha), activate similar signal transduction pathways, we examined the effect of TNF-alpha on SMIT mRNA levels and myo-inositol accumulation. In contrast to the effect of hyperosmolarity, TNF-alpha caused a time- and concentration-dependent decrease in SMIT mRNA levels and myo-inositol accumulation. The effect of TNF-alpha on myo-inositol accumulation was found in large-vessel endothelial cells (derived from the aorta and pulmonary artery) and cerebral microvessel endothelial cells. In bovine aorta and bovine pulmonary artery endothelial cells, TNF-alpha activated nuclear factor (NF)-kappa B. TNF-alpha also increased ceramide levels, and C2-ceramide mimicked the effect of TNF-alpha on SMIT mRNA levels and myo-inositol accumulation in bovine aorta endothelial cells. Pyrrolidinedithiocarbamate, genistein, and 7-amino-1-chloro-3-tosylamido-2-hepatanone, compounds that can inhibit NF-kappa B activation, partially prevented the TNF-alpha-induced decrease in myo-inositol accumulation. The effect of TNF-alpha on myo-inositol accumulation was also partially prevented by the protein kinase C inhibitor calphostin C but not by staurosporine. These studies demonstrate that TNF-alpha causes a decrease in SMIT mRNA levels and myo-inositol accumulation in cultured endothelial cells, which may be related to the activation of NF-kappa B.
Yorek
M A
MA
Department of Internal Medicine, University of Iowa, Iowa City 52246, USA.
Dunlap
J A
JA
Thomas
M J
MJ
Cammarata
P R
PR
Zhou
C
C
Lowe
W L
WL
D000818:Animals; D001011:Aorta; D002352:Carrier Proteins / Q000096:biosynthesis*; D002417:Cattle; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation; D016207:Cytokines / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D006801:Humans; D007294:Inositol / Q000378:metabolism*; D007700:Kinetics; D008565:Membrane Proteins; D051379:Mice; D008833:Microcirculation; D011651:Pulmonary Artery; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D027981:Symporters; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002352:Carrier Proteins; D016207:Cytokines; D006133:Growth Substances; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; C064769:N-acetylsphingosine; D027981:Symporters; D014409:Tumor Necrosis Factor-alpha; C073884:SLC5A3 protein, human; D007294:Inositol; D013110:Sphingosine